Solid-state imaging systems or imaging readers have been used, in both handheld and/or hands-free modes of operation, to electro-optically read symbol targets, such as one- and/or two-dimensional bar code symbols, each bearing elements, e.g., bars and spaces, of different widths and reflectivities, to be decoded, as well as other targets, such as forms, documents, labels, receipts, signatures, drivers' licenses, identification badges, payment/loyalty cards, and the like, each bearing one or more form fields, typically containing alphanumeric characters, images, or bar code symbols.
A known exemplary imaging reader includes a housing, either held by a user in the handheld mode, or supported on a support, such as a stand, a cradle, a docking station, or a support surface, in the hands-free mode; a window supported by the housing and aimed at the target; and a scan engine or module supported by the housing and having a solid-state imager (or image sensor or camera) with a sensor array of photocells or light sensors (also known as pixels), and an imaging lens assembly for capturing return light scattered and/or reflected from the target being imaged along an imaging axis through the window over a field of view, and for projecting the return light onto the sensor array to initiate capture of an image of the target over a range of working distances in which the target can be read. Such an imager may include a one- or two-dimensional charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) device and associated circuits for producing and processing electrical signals corresponding to a one- or two-dimensional array of pixel data over the field of view. These electrical signals are decoded and/or processed by a programmed microprocessor or controller into information related to the target being read, e.g., decoded data indicative of a symbol, or characters or marks indicative of text in a form field of a form, or into a picture indicative of a picture on the form.
A trigger is typically manually activated by the user to initiate reading in the handheld mode of operation. In the hands-free mode, the user may slide or swipe the target past the window in either horizontal and/or vertical and/or diagonal directions in a “swipe” mode. Alternatively, the user may present the target to an approximate central region of the window in a “presentation” mode. The choice depends on the type of target, operator preference, or on the layout of a workstation in which the reader is used. In the handheld mode, the user holds the reader in his or her hand at a certain working distance from the target to be imaged and initially aims the reader at the target. The user may first lift the reader from a countertop or like support surface, or from a support, such as a stand, a cradle, or a docking station. Once reading is completed, the user may return the reader to the countertop, or to the support, to resume hands-free operation.
Although the known imaging readers are generally satisfactory for their intended purpose, one concern relates to different formats used by different components. The imager is available as a monochrome or a color device. A monochrome imager generates an output data stream in a monochrome format and is generally preferred in a bar code symbol reading application, because, among other things, the monochrome imager generally has larger pixels and, thus, the monochrome imager has a better signal-to-noise ratio, as well as a better sensitivity to light due to the absence of color filters, as compared to color imagers. Although the controller is also available as a monochrome or a color device, most controllers used in modern computer equipment are configured as color controllers, which only accept output data streams from the imager in a color format.
The output data stream in the monochrome format has a plurality of pixel cells or slots, each containing pixel data indicative of the luminance, e.g., the intensity or brightness, of the captured return light detected by each pixel. The output data stream in the color format also has a plurality of pixel slots, but, in addition, also has a plurality of color cells or slots that contain color information, e.g., the blue difference chrominance (Cb), or the red difference chrominance (Cr), of the captured return light detected by each pixel. Since a color controller can only receive an output data stream in the color format, the absence of any color slots or color information in the monochrome format results in an incompatibility between these formats. The art has proposed addressing this incompatibility by using monochrome-to-color converter circuits, which add dummy cells or slots to the output data stream in the monochrome format, and which insert dummy data into these dummy slots. The dummy data do not contain any useful information relating to the image, but are merely provided to render the output data stream from the monochrome imager compatible with the color controller. The dummy data is discarded or ignored by the color controller.
Yet, the known converter circuits have not been altogether satisfactory for their intended purpose. The conversion process is very inefficient, particularly insofar as data bandwidth is concerned. The conversion process is also very slow, thereby rendering the reading performance sluggish.
Accordingly, there is a need for an apparatus for, and a method of, enhancing and optimizing target reading performance by converting a monochrome format of an output data stream from a monochrome imager to a color format required by a color controller without, among other things, using or relying on any such dummy data.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.